| 摘要 |
PROBLEM TO BE SOLVED: To control operation by accurately detecting momentary short power interruption. SOLUTION: A power source control circuit 12 sets a momentary power interruption signal, to be sent to a momentary power interruption counter 13 from an 'L' to an 'H' for a prescribed time, when a voltage monitor signal sent from a voltage monitoring circuit 14 becomes an 'L' from an 'H'. The counter 13 starts counting of a clock signal supplied from an RTC circuit 11, according to a momentary power interruption detection signal. The circuit 12 sets a reset signal to be sent to a CPU 9 from 'L' to 'H', when the voltage monitor signal sent from the circuit 14 is set from 'L' to 'H'. The CPU 9 specifies number of clock signals counted by the counter 13, when the reset signal is set from 'L' to 'H', and judges whether a drop of the power source voltage corresponds to the power interruption. The CPU 9 switches the operation according to the judged result, to accurately detect the power interruption and to control the operation. |
